Cool Spacewalk, Right? Get Ready for More—ISS Will Need Fixin'

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Cool Spacewalk, Right? Get Ready for More—ISS Will Need Fixin'

Peggy Whitson on her record-breaking eighth spacewalk in March 2017.

NASA

When astronaut Peggy Whitson pushed out of the International Space Station’s airlock on Tuesday morning, she was floating into history. Stipulated, Whitson was already a badass. But this extra-vehicular activity—an EVA, NASAspeak for a spacewalk—was Whitson’s 10th. That ties her for the American record. A PhD biochemist before she became an astronaut, Whitson has now spent more time in space outside a spacecraft than all but two other human beings.

Whitson was also floating into the future, though, and it seems sure to be filled with more urgent repairs like this one. The spacewalk was a “contingency EVA,” which—NASAspeak again, etymologically derived from Testpilot High Laconic and Scientific Detach-ese—means “serious emergency.” No one knows yet why a box full of computer boards called a Multiplexer-Demultiplexer failed, but NASA started building the ISS in 1998. The station is entering its third decade of life in orbit. More and more pieces are going to start breaking.

That’s not to say the astronauts can’t handle it. “Today’s EVA—they’re never routine, but it was among the more routine,” says Michael Lopez-Alegria, a retired astronaut and private space consultant, (He shares the 10-EVA American record, too, but has more total time in space than Whitson—for now.) “They’ve practiced it before, and the ground team has put together similar procedures on a similarly short fuse.”

For Tuesday’s spacewalk, Whitson and fellow astronaut Jack Fischer had to first build a new MDM from spare parts on board. And they’d just replaced this same MDM and its partner last month … after a previous contingency EVA in 2014 had replaced one of them, too. The station has 48 altogether; these two problematic ones regulate radiators, solar arrays, and cooling loops—temperature and power. “If one of them fails and we’re down to the backup for that box, we are one more failure away from something near catastrophic,” says Terry Soich, a project engineering manager for human space at Honeywell Aerospace, which manufactured the MDMs. “They jump on that pretty quick.”

The reality is, they’re going to continue to have problems. As all that equipment gets older, you’re going to have a higher incidence of failures.

Daryl Shuck, Honeywell Aerospace

To do the job, Whitson had to make her way out to the Starboard Zero truss, unbolt the MDM with basically a space power wrench, clean out the bolt-holes with a cold-gas gun (with Fischer’s help), and bolt in the new one. They had to hold onto the broken MDM, because NASA and Honeywell want to know what went wrong, and if they put it down it would have just, like, floated away.

Planning and preparing for the 2014 MDM replacement spacewalk took a couple weeks; this crew did it in slightly more than two days. Whitson and Fischer—who also installed a couple antennas on the EVA—started early and finished ahead of schedule. “It’s just a great testament to the machine that this EVA team, on the ground and the crews on orbit, have become,” Lopez-Alegria says. “They made it look easy.”

But, gosh, it sure would be nice to know what was wrong with the MDMs the astronauts keep having to fix. “It showed similar, but not identical, symptoms to the event in 2014 in that the failure was not preceded by any signs of bad telemetry,” says Daniel Huot, a NASA spokesperson. The box they swapped out back then had lasted longer; it had been in continuous service since 2002.

So what happened this time? “The short answer is, they’re getting old,” Soich says. “Until we get it back inside and test it, we’re not going to know. We requested that data from the crew.”

The MDMs were supposed to last a decade; they’ve nearly doubled their operational lifespan. But that’s true for a lot of the pieces that comprise the ISS. And that could be a problem. The station was supposed to have a 15-year mission, but NASA keeps extending its time in orbit. The clock just got reset to 2024, maybe longer. “NASA has anticipated these failures. They know they’re on somewhat borrowed time when they’re that far over the designed life,” says Daryl Schuck, a customer business manager at Honeywell Aerospace. “The reality is, they’re going to continue to have problems. As all that equipment gets older, you’re going to have a higher incidence of failures.”

Not to knock as amazing a piece of technology as the ISS—it’s still safe and functioning nominally, as the NASA people say. But at this point it’s a little bit like a 20-year-old car. Even if it’s a classic, you’re probably not going to put in a new sound system. It’s a hub for space research, albeit an expensive one. NASA has committed to furthering commercial space businesses; right now, the ISS is a destination for SpaceX and, perhaps someday, its competitors. If it goes away, what happens to them? “We’d love to see more upgrades. NASA is, I think, trying to fly as economically as possible,” Schuck says. “You could preempt those failures with preventative maintenance, but you’d spend all your time doing these preemptive changes and not doing a whole lot of science.”

As good at handling contingency spacewalks as the astronauts and ground crews are, they’re not supposed to become the new normal. Then again, more frequent maintenance spacewalks would have an upside: The cosmonaut Anatoly Solovyev still holds the world record, with 16 EVAs and over 82 hours in space. But Commander Whitson’s still up there, space power wrench at the ready. Just saying.

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